Typically a telescopic tube arrangement includes a separate pin which can be inserted through aligned holes in the two tubes. This arrangement is disadvantageous in that the pin can be lost or damaged when removed so that the tubes cannot be locked in a required position.
Alternatively a spring biased pin is mounted inside the inner tube and has a rounded end portion which projects outwardly from the inner tube to engage into a hole in the outer tube. This arrangement is generally relatively crude and loose with low accuracy of location and a low level of communication of longitudinal force or rotational torque between the tubes.